Epoxy based compositions have been utilized in various applications, including the making of articles for use on motor vehicles. For example, these thermoset polymers are suitable for use in applications such as sealants, adhesives, moldings, and decorative features. Depending upon the application, such compositions have typically been either formed and cured prior to application on the vehicle or applied onto the vehicle and cured in place. Alternatively, some epoxy based compositions have been only partially cured prior to application on the vehicle and then additionally cured after being applied. The partially cured state of the epoxy composition provides dimensional stability to an article made with the composition and thus helps the article retain its shape during subsequent processing. The use of thermoset epoxy based compositions on motor vehicles often requires the curing of the epoxy under strict manufacturing timing constraints.
It is desirable for vehicle related articles produced from epoxy based compositions to match the color of other portions of the vehicle and, thereby, provide a desirable aesthetic appearance to the vehicle. The vehicle related articles produced from epoxy based compounds may be painted to match the color of other portions of the vehicle. Additionally, other epoxy based compositions that will not be painted may also require certain colors to match surrounding vehicle parts or to disguise the use of the epoxy based composition. The epoxy compositions do not always result in a desirable color upon polymerization.
It has typically been difficult for the epoxy portion of such articles to be painted "on-line" along with the rest of the vehicle because the paint is often brittle and tends to crack and flake off the surface of the epoxy portion of the article. This is particularly true with the electrostatically applied paint typically used in the automotive industry. In response to this problem, such articles have been painted "off-line" in a separate operation using specially formulated paints. The "off-line" application of a finished color coat does not always result in an adequate color match. Additionally, the portions of the vehicle to be painted are first primed with a base coat prior to the application of a finished color coat. The entire vehicle is then painted. Under these circumstances, if the color of the article does not closely match that of the primer, the painted article may appear different from that of the primed portions of the vehicle.
Alternatively, epoxy based compositions have been formulated with pigments to provide color matching with other portions of the vehicle. The utilization of pigments, however, can also result in an undesirable aesthetic difference between the article and the other portions of the vehicle. Additionally, the use of pigments in photo-polymerizable epoxy compositions may inhibit photo-polymerization.
Thus, it is desirable to provide an accelerator in an epoxy based composition in order to improve the curing time of the composition. Additionally, it is desirable to provide or impart specific colors to the cured, or partially cured, composition to achieve a desirable aesthetic appearance without adversely affecting the polymerization of the epoxy compositions.